The Applicant's Assignee's U.S. Pat. No. 6,017,354, entitled INTEGRATED SYSTEM FOR POWERED SURGICAL TOOLS, issued Jan. 25, 2000, and incorporated herein by reference, describes a surgical tool system with a handpiece that is removably attached to a control console. Internal to the handpiece is a memory, a NOVRAM. The NOVRAM contains data that describes the operating characteristics of the handpiece. For example, if the handpiece includes a motor, its NOVRAM includes data indicating the maximum speed at which the motor should run and, for given speeds, the maximum torque the motor is allowed to develop. Each time a new handpiece is attached to the control console, the data in the handpiece NOVRAM is read by a complementary processor in the control console. The control console, based on the handpiece NOVRAM data, then supplies the appropriate energization signal to the handpiece motor.
An advantage of the foregoing system is that it allows a single control console to be used to supply the energization signals that are applied to the handpiece that have different power consuming units, such as motors. Thus, a single control console can be used to operate a first handpiece with a motor that rotates at speeds under 3,000 RPM and requires 350 Watts or more of power, a second handpiece that has a motor that operates at speeds over 70,000 RPM and that requires approximately 150 Watts of power and a third handpiece that operates at speeds between 10,000 to 40,000 RPM and that requires only 40 Watts of power.
In most surgical systems, the handpiece is not the actual component that is applied to the surgical site in order to accomplish a surgical task. These components are, what are referred to as cutting accessories.
Typically, a single handpiece is used to actuate a number of different types of cutting accessories. For example, a handpiece designed to perform some forms of ear, nose and throat surgery is designed to actuate both burrs and cutters. Burrs are cutting accessories designed to selectively shape and remove hard tissue, bone. Cutters are cutting accessories that are employed to selectively shape and remove soft tissue such as sinus membrane tissue.
While a single handpiece is designed to actuate different types of cutting accessories, the accessories themselves often have different operating characteristics. For example, some burrs may have a preferred operating speed of 6,000 RPM and may be designed to operate at speeds of up to 10,000 RPM. In contrast, some cutters may have a preferred operating speed of 2,000 RPM and may be designed to operate at a maximum speed of 5,000 RPM. Moreover, some cutting accessories are operated in a different manner than other cutting accessories. For example, a burr is driven, rotated, in a single direction. A cutter is typically oscillated. In other words, when a cutter is actuated, it is typically rotated through an arc of X degrees in a first direction and then rotated in the opposite direction through the same arc. Once this first rotation cycle is complete, the motor driving the cutter repeats this rotational pattern.
Often, during the course of a single surgical procedure, the surgeon will want to apply two or more different cutting accessories to the surgical site in order to accomplish the procedure. Typically, the surgeon will use a single handpiece to actuate these different cutting accessories. Each time the surgeon attaches a different type of cutting accessory to the handpiece, it may be necessary for the surgeon or other operating room personnel to reconfigure the surgical system used to drive the cutting accessory to set it for the specific characteristics of that accessory. When surgical personnel have to do this during the course of a surgical procedure, it can increase the overall time it takes for the procedure to be performed. This is contrary to one of the goals of modern surgery which is that it is desirable to perform a surgical procedure as quickly as possible in order to hold the overall time a patient is kept under anesthesia to a minimum.
Moreover, having to have an individual in the operating room set the surgical system to the operating characteristics of the cutting accessory that the system is being used to operate introduces the possibility that, due to human error, these characteristics will be improperly entered.
There have been some efforts at providing cutting accessories with type-identifying indicators, typically magnets. The handpieces to which these accessories are attached are provided with sensors. These sensors detect the presence/absence of the magnets and generate signals representative of what was sensed back to the control console. The processor in the control console, based on the signals from the handpiece sensors, then configures the system.
The above system, while of some utility, only provides a limited amount of data about the cutting accessory attached to the system handpiece. This is because, due to space considerations, only a limited number of indicators can be mounted to a cutting accessory and only a limited number of sensors can be fitted in the head end of the handpiece designed to actuate the accessory. For example, known commercial systems of this design have handpieces with two sensors. Each sensor is designed to detect the presence/absence of a separate cutting accessory-mounted magnet. Thus, these systems simply provide 2 bits of data. Even if it were possible for the number of magnets in the cutting accessories and the number of complementary handpiece sensors to be doubled, the resultant system would only be able to provide 4 bits of accessory specific data.
Thus, in the current systems, the indicators mounted to a cutting accessory are only employed to provide data that describes a basic operating characteristic of the accessory or that describes its type. For example, the indicator may be employed to describe basic speed and torque ranges of the cutting accessory or, for example, that the accessory is a burr. Regardless of the specific nature of this data, the control console processor, uses the data to reference complementary control data in a look-up table or other circuitry internal to the control console. The actual regulation of the handpiece is controlled by reference to this previously stored characteristic-data.
Thus, in the foregoing cutting accessory recognition system, the actual control of the handpiece is based on operating parameters that have been previously loaded into the control console. If a new accessory is provided that has operating characteristics different than those that have been loaded into the control console, the console will not automatically configure itself to operate the handpiece in accordance with those parameters. In order for this control to be accomplished, the control console has to be loaded with the new operating characteristic data. Moreover, given the limited amount of data that can be read from the indicators of the current systems, these data may be insufficient to provide all the information a control console could use to regulate its operation based on the characteristics of the attached cutting accessory.